System to monitor irregular activity

ABSTRACT

A computer-implemented method includes receiving item data at a network-based computer system, the item data related to an item categorized in at least a first category of a plurality of categories supported by the network-based computer system and including an item price-based value associated with the item. A category-specific threshold price-based value, for the first category of the plurality of categories supported by the network-based computer system, is automatically determined. The item data is automatically determined to the irregular, based on the item price-based value associated with the item and the category-specific threshold price-based value for the first category of the plurality of categories supported by the network-based computer system. Responsive to the determination that the item data is irregular, an entity associated with the item is restricted from using the network-based computer system.

RELATED APPLICATIONS

The present application is a Continuation of U.S. patent applicationSer. No. 11/158,651, filed Jun. 22, 2005, which is a Continuation ofU.S. patent application Ser. No. 09/661,168, filed Sep. 13, 2000, bothof which are incorporated herein by reference.

TECHNICAL FIELD

The present application relates generally to the monitoring irregularactivity in a computer-system.

BACKGROUND

Network-based transaction facilities (e.g., business-to-business,business-to-consumer and consumer-to-consumer Internet marketplaces andretailers) provide convenience of access to users of such facilities andon-line communities. Information regarding sales made throughnetwork-based transaction facilities may be automatically extracted andreported for any desired time interval—hourly, daily, weekly, monthly,etc. This information is useful to the facilities for a variety ofreasons including record keeping, generating statistics, calculatingrevenue, etc.

For example, an Internet-based retailer may generate a report listingthe items sold during the day and the revenue generated by the sales. AnInternet-based bookstore may, for example, generate reports listing thenumber of books sold during the past month in a specific category or bya specific author. Such statistics are useful in assisting a purchaserwith a buying decision or assisting the retailer with stockingdecisions.

For a network-based transaction facility, such as an Internet-basedauction facility, and its users, information regarding sales isparticularly important for setting fees and providing price guidance tousers. Fees may be set based on volume or price of the items sold forindividual users. The network-based auction facility may use salesinformation and statistics to determine how to set fees. Thenetwork-based auction facility may further use information generated ona periodic basis to guide sellers in setting prices at which to selltheir items or buyers in bidding for items by indicating the averageprice or price range of the type of product being sold. Thus, there is aneed for accurate reporting of information.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example and notlimitation in the figures of the accompanying drawings, in which likereferences indicate similar elements and in which:

FIG. 1 is a block diagram illustrating an exemplary network-basedtransaction facility in the form of an Internet-based auction facility;

FIG. 2 is a block diagram illustrating an exemplary database that atleast partially implements and supports the Internet-based auctionfacility of FIG. 1;

FIGS. 3 a and 3 b are diagrammatic representations of an exemplaryembodiment of a transaction record table;

FIG. 4 is a flow diagram of one embodiment of an irregular activitymonitoring and automatic notification system;

FIG. 5 is a flow diagram of a second embodiment of an irregular activitymonitoring and automatic notification system;

FIG. 6 is a flow diagram of a third embodiment of an irregular activitymonitoring and automatic notification system;

FIG. 7 is a flow diagram of a fourth embodiment of an irregular activitymonitoring and automatic notification system;

FIG. 8 is a flow diagram of a fifth embodiment of an irregular activitymonitoring and automatic notification system;

FIG. 9 is a block diagram of one embodiment of a computer systemsuitable for practicing the present invention.

DETAILED DESCRIPTION

A method and system for monitoring and automatically reporting irregularactivity on a network-based transaction facility are described. In thefollowing description, for purposes of explanation, numerous specificdetails are set forth in order to provide a thorough understanding ofthe present invention. It will be evident, however, to one skilled inthe art that the present invention may be practiced without thesespecific details.

Terminology

For the purposes of the present specification, the term “transaction”shall be taken to include any communications between two or moreentities and shall be construed to include, but not be limited to,commercial transactions including sale and purchase transactions,auctions and the like. The term “suspect” shall be taken to indicaterequiring further investigation or scrutiny. The term “irregular” shallbe taken to indicate a derivation from a norm or an exceeding ofboundaries or a range.

Transaction Facility

FIG. 1 is a block diagram illustrating an exemplary network-basedtransaction facility in the form of an Internet-based auction facility10. While an exemplary embodiment of the present invention is describedwithin the context of an auction facility, it will be appreciated bythose skilled in the art that the invention will find application inmany different types of computer-based, and network-based, commercefacilities.

The auction facility 10 includes one or more of a number of types offront-end servers, namely page servers 12 that deliver web pages (e.g.,markup language documents), picture servers 14 that dynamically deliverimages to be displayed within Web pages, listing servers 16, CGI servers18 that provide an intelligent interface to the back-end of facility 10,and search servers 20 that handle search requests to the facility 10.E-mail servers 21 provide, inter alia, automated e-mail communicationsto users of the facility 10.

The back-end servers include a database engine server 22 including anirregular activity monitoring system 27, a search index server 24 and acredit card database server 26, each of which maintains and facilitatesaccess to a respective database.

The Internet-based auction facility 10 may be accessed by a clientprogram 30, such as a browser (e.g., the Internet Explorer distributedby Microsoft Corp. of Redmond, Wash.) that executes on a client machine32 and accesses the facility 10 via a network such as, for example, theInternet 34. Other examples of networks that a client may utilize toaccess the auction facility 10 include a wide area network (WAN), alocal area network (LAN), a wireless network (e.g., a cellular network),or the Plain Old Telephone Service (POTS) network.

Database Structure

FIG. 2 is a database diagram illustrating an exemplary database 23,maintained by and accessed via the database engine server 22, which atleast partially implements and supports the auction facility 10.Database engine server 22 includes an irregular activity monitoringsystem 27 which performs algorithms to remove irregular and suspect dataitems from data representations, as described below with reference toFIGS. 4-8.

The database 23 may, in one embodiment, be implemented as a relationaldatabase, and includes a number of tables having entries, or records,that are linked by indices and keys. In an alternative embodiment, thedatabase 23 may be implemented as collection of objects in anobject-oriented database.

Database 23 includes an item table 40, which contains a record for eachitem being auctioned on the auction facility 10. An item record in itemtable 40 may include, inter alia, an identification number, amarketplace indicator, sale type, title, location, seller, owner,category, quantity, bid count, sale start date, sale end date, highestbidder identification, billing currency, etc. The database 23 alsoincludes an item ended table 42, linked to the item table 40, and anitem archived table 44, linked to the item ended table 42. Each itemfrom item table 40 is moved to the item ended table 42 two to three daysafter the end of the auction for that item. Each item from item endedtable 42 is moved to item archived table 44 three months after the endof the auction for that item.

The item table 40 is also linked to item description table 50 and itemdescription ended 52. Item description table 50, item description endedtable 52 and item description archived table 54 may each include, interalia, a description of each item in the item table, an identificationfor the item and a marketplace indicator for the item. Each itemdescription from item description table 50 is moved to the itemdescription ended table 52 two to three days after the end of theauction for that item. Each item description from item description endedtable 52 is moved to item description archived table 54 three monthsafter the end of the auction for that item.

A number of other tables are also shown to be linked to the item table40, namely a transaction record table 200, a categories table 70 and anirregular item table 80. The irregular item table 80 may also be linked(not shown) to the transaction record table 200. Item information fromitem records in item table 40 is entered into transaction record table200 upon the completion of a successful auction.

FIGS. 3 a and 3 b are diagrammatic representations of an exemplaryembodiment of the transaction record table 300 that is populated withrecords, or entries, for completed, or ended, transactions (e.g.,auctions) that have been facilitated by the auction facility 10. Thetable 300 includes an item identifier column 310 for each entry, and atleast one price-based value column 320, 330 indicating, for example, thehighest bid for the entry (or selling price) 320 or a fee, based on thehighest bid 330, charged the seller by the network-based auction site10. The item identifier entry may be an item number including a pointerto further item information in item table 40. The item information initem table 40 may include a pointer to category information incategories table 70.

An irregular flag column 340 stores a value 301-304 indicating whetherthe entry is irregular. A seller id column 350 and a bidder id column360 store a user identifier for each of the seller of an item and thehighest bidder (or purchaser) for the item, the user identifiercomprising a pointer to further user information stored in a user table(not shown).

It should be noted that only one of the selling price column 320 orprice-based fee column 330 is necessary for the operation of the presentinvention. Further, the irregular flag column 340, seller id column 350and bidder id column 360 are also not required for the operation of theirregular activity monitoring and automatic reporting system. In theembodiment shown in FIGS. 3 a and 3 b, monitoring of the irregularactivity is done using the transaction record table 300. In otherembodiments, the irregular activity may be monitored and reported in anytable that used by the auction site for reporting or representing data.

In FIGS. 3 a and 3 b, items 1-4 in column 310 are linked to the samecategory. The selling prices of items 1-4 are $2500, $150,000, $1800 and$1950, respectively. If the category is computers, for example, thecategory may be assigned an irregular activity threshold of $15,000 oranother amount that would indicate that the item or the bid is irregular(or outside the normal range). In FIG. 3 a, all of the irregular flagvalues 301-304 in column 340 are initially assigned a value of 0 whenthe item information is first entered in the transaction record table300.

In FIG. 3 b, item 2's irregular flag 302 has been changed from 0 to 1 toindicate that item 2 has some irregular activity associated with it. Itshould be noted that, in one embodiment, an entry is only created in thetransaction record table 300 for transactions that have beenestablished, for example, by the conclusion of an auction process, or bysome other offer and acceptance mechanism between the purchaser and theseller. Thus, the irregular activity monitoring and automaticnotification system, which may include changing the irregular flagvalue, may be triggered after information has been entered into atransaction record table 300, for example, for each category for allauctions in that category ending at a specific time.

The irregular flag may be implemented so that the irregular flag may belater changed back to 0, after further investigation. In anotherembodiment, the irregular flag may be implemented so that it may not bechanged back to 0 once it has been changed to 1.

When irregular activity has been found, an email may be sent to theseller and/or bidder at an address associated with the user identifierof the seller and/or bidder. The seller and/or bidder may further bebanned from participation on the auction site by using the pointerlinking to the user table to update a “irregular_user” or similar fieldin the user record of the seller and/or bidder.

The irregular flag 301-304 in FIGS. 3 a and 3 b may be updated based onanother price-based value, such as a price-based fee 330, for example.An auction site 10 may charge sellers fees based on the selling price ofan item. Thus, the auction site may use the formula for determining feesto determine a threshold fee for monitoring irregular activity. In FIGS.3 a and 3 b, the threshold fee for the category computers, for example,may be $200, based on a threshold price of $15,000. In anotherembodiment, the threshold fee may be simply the average fee plus a setamount, such as $300, for example. Thus, if the average fee forcomputers is $40, for example, then the threshold fee may be $340. Manyother algorithms may be used to determine a threshold price-based value,such as a threshold price or threshold price-based fee.

The threshold price-based value may also be determined based on thecurrency of the transaction, the category of the transaction, or thegeographic location of the transaction. For example, a table may be usedto determine threshold prices for items where the rows of the tablerepresent the categories of the item and the columns represent thecurrency of the transaction. The threshold values may be listed in U.S.dollars for uniformity. Although the transaction is completed inJapanese yen, the threshold value will be listed in dollars and thehighest bid will be converted from yen to dollars to compare whether thethreshold value has been exceeded. Thus, a transaction completed inJapanese yen won't be limited to the threshold set for transactions inU.S. dollars and transactions in U.S. dollars won't be limited tothresholds set for Japanese yen.

FIG. 4 is a flow diagram of one embodiment of an irregular activitymonitoring and automatic notification system. At processing block 401,data is received, for example in the transaction record table 300,having at least one price-based value. Although the process is describedwith respect to transaction record table 300, it will be appreciatedthat the following processes may performed with any set of data at anylocation at auction site 10.

At processing block 402, a counter n is set to 0. At processing block403, the irregular activity monitoring system 27 checks to see if aprice-based value of Item (n) of a set of items has a value greater thana predetermined value. As discussed above, the set of items may be itemsfrom the same category which had transactions established, by the endingof an auction, for example, at the same time. The predetermined valuewould depend on which price-based value is being examined, the currency,the geographic area, the category of the item or any other parameterthat may indicate different threshold values to establish irregularactivity.

If the price-based value of item(n) is not greater than thepredetermined value, the irregular activity monitoring system 27 skipsto processing block 405, as described below.

If the price-based value of item(n) has a value greater than thepredetermined value, at processing block 404, the item(n) is removedfrom further representations of the data, which may include, forexample, reports or statistics based on established transactions. Theirregular activity monitoring system 27 then proceeds to processingblock 405 which checks whether the end of the set of items has beenreached by comparing n to End. If n equals End, the system concludeschecking for irregular activity at processing block 407.

If n does not equal End, the counter is incremented by 1 and theirregular activity monitoring system 27 returns to processing block 403to check then next item in the set of items.

It will be appreciated that the irregular activity monitoring system 27may be implemented as part of a larger application or may be implementedby itself.

FIG. 5 is a flow diagram of a second embodiment of an irregular activitymonitoring and automatic notification system. At processing block 501,data is received including at least one item record having at least oneprice-based value associated with the item, as discussed above withrespect to FIG. 4. At processing block 502, a counter n is set to 0.

At processing block 503, the price-based value of item(n) of a set ofitems is compared to a predetermined price-based value. If theprice-based value of item(n) is not greater than the predeterminedvalue, the irregular activity monitoring system 27 goes on to processingblock 505.

If the price-base value of item(n) is greater than the predeterminedvalue, at processing block 504, the value of an irregular flagassociated with item(n) is changed from 0 to 1. The system then proceedsto processing block 505 where the system checks to see if the end of theset of items has been reached. If the end of the set has not beenreached, at processing block 506, the counter n is incremented by 1 andthe system proceeds to processing block 503 to check the price-basedvalue of the next item. If the end of the set has been reached, thesystem proceeds to processing block 507 where a report or other datarepresentation is generated where the data representation only includesitems having an irregular flag value of 0.

FIG. 6 is a flow diagram of a third embodiment of an irregular activitymonitoring and automatic notification system. At processing block 601,data is received including at least one item record having at least oneprice-based value associated with the item, as discussed above withrespect to FIG. 4. At processing block 602, a counter n is set to 0.

At processing block 603, the price-based value of item(n) of a set ofitems is compared to a predetermined price-based value. If theprice-based value of item(n) is not greater than the predeterminedvalue, the irregular activity monitoring system 27 goes on to processingblock 605.

If the price-base value of item(n) is greater than the predeterminedvalue, at processing block 604, the value of an irregular_flagassociated with item(n) is changed from 0 to 1. The system then proceedsto processing block 605 where the system checks to see if the end of theset of items has been reached. If the end of the set has not beenreached, at processing block 606, the counter n is incremented by 1 andthe system proceeds to processing block 603 to check the price-basedvalue of the next item.

If the end of the set has been reached, the system proceeds toprocessing block 607 where each item having an irregular flag value of 1is investigated. At processing block 608, the irregular flag values ofall the transactions that are found to be legitimate are reset to 0. Atprocessing block 609, a report or other data representation is generatedwhere the data representation only includes items having an irregularflag value of 0.

FIG. 7 is a flow diagram of a fourth embodiment of an irregular activitymonitoring and automatic notification system. At processing block 701,data is received including at least one item record having at least oneprice-based value associated with the item. At processing block 702, acounter n is set to 0.

At processing block 703, the price-based value of item(n) of a set ofitems is compared to a predetermined price-based value. If theprice-based value of item(n) is not greater than the predeterminedvalue, the irregular activity monitoring system 27 goes on to processingblock 705.

If the price-base value of item(n) is greater than the predeterminedvalue, at processing block 704, the value of an irregular_flagassociated with item(n) is changed from 0 to 1. The system then proceedsto processing block 705 where the system checks to see if the end of theset of items has been reached. If the end of the set has not beenreached, at processing block 706, the counter n is incremented by 1 andthe system proceeds to processing block 703 to check the price-basedvalue of the next item.

If the end of the set has been reached, the system proceeds toprocessing block 707 where a report or other data representation isgenerated where the data representation includes all items includingitems having an irregular flag value of 1. However, the records for allitems having an irregular flag value of 1 are disabled so that the itemsare not used for any computations or statistics or other purposes,although the items appear in the data representations.

At processing block 708, all items having an irregular flag value of 1are investigated. At processing block 709, the irregular flag values ofall the transactions that are found to be legitimate are reset to 0 sothat the item records may be included in computations and statistics.

FIG. 8 is a flow diagram of a fifth embodiment of an irregular activitymonitoring and automatic notification system. At processing block 801,data is received including at least one item record having at least oneprice-based value associated with the item. At processing block 802, acounter n is set to 0.

At processing block 803, the price-based value of item(n) of a set ofitems is compared to a predetermined price-based value. If theprice-based value of item(n) is not greater than the predeterminedvalue, the irregular activity monitoring system 27 goes on to processingblock 805.

If the price-base value of item(n) is greater than the predeterminedvalue, at processing block 804, the value of an irregular_flagassociated with item(n) is changed from 0 to 1. The system then proceedsto processing block 805 where the system checks to see if the end of theset of items has been reached. If the end of the set has not beenreached, at processing block 806, the counter n is incremented by 1 andthe system proceeds to processing block 803 to check the price-basedvalue of the next item.

If the end of the set has been reached, the system proceeds toprocessing block 807 where a report or other data representation isgenerated where the data representation only includes items having anirregular flag value of 1. At processing block 808, all of the items inthe report generated by processing block 807 are investigated. Atprocessing block 809, the irregular flag values of all the transactionsthat are found to be legitimate are reset to 0 so that the item recordsare available for all computations, statistics, etc.

In summary, it will be appreciated that the above described interfaces,and underlying technologies, provide a convenient vehicle for theinputting of feedback, comments or opinions regarding multiple items, ortransactions, via a single user interface.

FIG. 9 shows a diagrammatic representation of machine in the exemplaryform of a computer system 900 within which a set of instructions, forcausing the machine to perform any one of the methodologies discussedabove, may be executed. In alternative embodiments, the machine maycomprise a network router, a network switch, a network bridge, PersonalDigital Assistant (PDA), a cellular telephone, a web appliance or anymachine capable of executing a sequence of instructions that specifyactions to be taken by that machine.

The computer system 900 includes a processor 902, a main memory 904 anda static memory 906, which communicate with each other via a bus 908.The computer system 900 may further include a video display unit 910(e.g., a liquid crystal display (LCD) or a cathode ray tube (CRT)). Thecomputer system 900 also includes an alpha-numeric input device 912(e.g. a keyboard), a cursor control device 914 (e.g. a mouse), a diskdrive unit 916, a signal generation device 920 (e.g. a speaker) and anetwork interface device 922

The disk drive unit 916 includes a machine-readable medium 924 on whichis stored a set of instructions (i.e., software) 926 embodying any one,or all, of the methodologies described above. The software 926 is alsoshown to reside, completely or at least partially, within the mainmemory 904 and/or within the processor 902. The software 926 may furtherbe transmitted or received via the network interface device 922. For thepurposes of this specification, the term “machine-readable medium” shallbe taken to include any medium that is capable of storing or encoding asequence of instructions for execution by the machine and that cause themachine to perform any one of the methodologies of the presentinvention. The term “machine-readable medium” shall accordingly be takento include, but not be limited to, solid-state memories, optical andmagnetic disks, and carrier wave signals.

Thus, a method and system for harvesting feedback information, comments,and opinions regarding multiple items from users of a network-basedtransaction facility have been described. Although the present inventionhas been described with reference to specific exemplary embodiments, itwill be evident that various modifications and changes may be made tothese embodiments without departing from the broader spirit and scope ofthe invention. Accordingly, the specification and drawings are to beregarded in an illustrative rather than a restrictive sense.

1. A computer-implemented method comprising: receiving item data at amachine of a network-based computer system, the item data related to anitem categorized in at least a first category of a plurality ofcategories supported by the network-based computer system and includingan item price-based value associated with the item; determining acategory-specific threshold price-based value of the first category;automatically determining at the machine that the item data isirregular, based on the item price-based value and the category-specificthreshold price-based value; and responsive to the determination thatthe item data is irregular, causing the machine to restrict an entityassociated with the item from using the network-based computer system.2. The computer-implemented method of claim 1 further comprising:communicating an electronic message to the entity associated with theitem.
 3. The computer-implemented method of claim 2, wherein thecommunicating of the electronic message includes sending an e-mailmessage to at least one of a seller or a buyer of the item, the e-mailmessage addressed to an address associated with at least one of theseller or the buyer of the item.
 4. The computer-implemented method ofclaim 1 further comprising: responsive to the determination that theitem data is irregular, setting an irregular item flag of the item data.5. The computer-implemented method of claim 4 further comprising:determining that the item data is legitimate; and responsive to thedetermination that the item data is legitimate, unsetting the irregularitem flag of the item data.
 6. The computer-implemented method of claim1, wherein the item price-based value is a price of the item, the priceof the item being at least one of a selling price or a bid price.
 7. Thecomputer-implemented method of claim 1, wherein the item price-basedvalue is a fee set by the network-based computer system based on aselling price of the item.
 8. The computer-implemented method of claim 1further comprising: removing the item data determined to be irregularfrom an item database of the network-based computer system.
 9. Thecomputer-implemented method of claim 1 further comprising: generating areport based on at least one of the item data or an item database of thenetwork-based computer system, the item data determined as irregular.10. The computer-implemented method of claim 1, wherein the determiningof the category-specific threshold price-based value includes readingthe category-specific threshold price-based value from a table ofprice-based values.
 11. The computer-implemented method of claim 1further comprising: storing an entity identification of the entityassociated with the item in an irregular entity database.
 12. A systemcomprising: means for receiving item data at a machine of anetwork-based computer system, the item data related to an itemcategorized in at least a first category of a plurality of categoriessupported by the network-based computer system and including an itemprice-based value associated with the item; means for determining acategory-specific threshold price-based value of the first category;means for automatically determining at the machine that the item data isirregular, based on the item price-based value and the category-specificthreshold price-based value; and means, responsive to the determinationthat the item data is irregular, for causing the machine to restrict anentity associated with the item from using the network-based computersystem.
 13. A system comprising: a database to receive and store itemdata, the item data related to an item categorized in at least a firstcategory of a plurality of categories supported by a network-basedcomputer system and including an item price-based value associated withthe item; a database engine server including an irregular activitymonitoring system, the irregular activity monitoring system to:determine a category-specific threshold price-based value of the firstcategory; determine that the item data is irregular, based on the itemprice-based value associated with the item and the category-specificthreshold price-based value of the first category; and responsive to thedetermination that the item data is irregular, restrict an entityassociated with the item from using the network-based computer system.14. The system of claim 13, wherein the irregular activity monitoringsystem communicates an electronic message to the entity associated withthe item.
 15. The system of claim 14, wherein the irregular activitymonitoring system sends an e-mail message to at least one of a seller ora buyer of the item, the e-mail message addressed to an addressassociated with at least one of the seller or the buyer of the item. 16.The system of claim 13, wherein the irregular activity monitoringsystem, responsive to the determination that the item data is irregular,sets an irregular item flag of the item data.
 17. The system of claim16, wherein the irregular activity monitoring system determines that theitem data is legitimate; and responsive to the determination that theitem data is legitimate, unsets the irregular item flag of the itemdata.
 18. The system of claim 13, wherein the item price-based value isa price of the item, the price of the item being at least one of aselling price or a bid price.
 19. The system of claim 13, wherein theitem price-based value is a fee set by the network-based computer systembased on a selling price of the item.
 20. The system of claim 13,wherein the irregular activity monitoring system removes the item datadetermined to be irregular from an item database of the network-basedcomputer system.
 21. The system of claim 13, wherein the irregularactivity monitoring system generates a report based on at least one ofthe item data or an item database of the network-based computer system,the item data determined as irregular.
 22. The system of claim 13,wherein the irregular activity monitoring system, in determining thecategory-specific threshold price-based value, reads thecategory-specific threshold price-based value from a table ofprice-based values.
 23. The system of claim 13, wherein the irregularactivity monitoring system stores an entity identification of the entityassociated with the item in an irregular entity database.
 24. Amachine-readable medium comprising a set of instructions, which whenexecuted by one or more processors of a machine at a network-basedcomputer system, causes the machine to: receive item data at thenetwork-based computer system, the item data related to an itemcategorized in at least a first category of a plurality of categoriessupported by the network-based computer system and including an itemprice-based value associated with the item; determine acategory-specific threshold price-based value of the first category;automatically determine at the machine that the item data is irregular,based on the item price-based value and the category-specific thresholdprice-based value; and responsive to the determination that the itemdata is irregular, cause the machine to restrict an entity associatedwith the item from using the network-based computer system.
 25. Acomputer-implemented method comprising: receiving item data at a machineof a network-based computer system, the item data related to an itemcategorized in at least a first category of a plurality of categoriessupported by the network-based computer system and including an itemprice-based value associated with the item; determining acategory-specific threshold price-based value of the first category;automatically determining at the machine that the item data isirregular, based on the item price-based value and the category-specificthreshold price-based value; and responsive to the determination thatthe item data is irregular, setting an irregular item flag of the itemdata.
 26. The method of claim 25 further comprising: responsive to thedetermination that the item data is irregular, causing the machine torestrict an entity associated with the item from using the network-basedcomputer system.
 27. The method of claim 25 further comprising: storingan entity identification of the entity associated with the item in anirregular entity database.
 28. The method of claim 25 furthercomprising: communicating an electronic message to an entity associatedwith the item.
 29. The method of claim 28, wherein the communicating ofthe electronic message includes sending an e-mail message to at leastone of a seller or a buyer of the item, the e-mail message addressed toan address associated with at least one of the seller or the buyer ofthe item.
 30. The method of claim 25 further comprising: determiningthat the item data is legitimate; and responsive to the determinationthat the item data is legitimate, unsetting the irregular item flag ofthe item data.
 31. The method of claim 25, wherein the item price-basedvalue is a price of the item, the price of the item being at least oneof a selling price or a bid price.
 32. The method of claim 25, whereinthe item price-based value is a fee set by the network-based computersystem based on a selling price of the item.
 33. The method of claim 25further comprising: removing the item data determined to be irregularfrom an item database of the network-based computer system.
 34. Themethod of claim 25 further comprising: generating a report based on atleast one of the item data or an item database of a network-basedcomputer system.
 35. The method of claim 25, wherein the determining ofthe category-specific threshold price-based value includes reading thecategory-specific threshold price-based value from a table ofprice-based values.
 36. A system comprising: means for receiving itemdata at a machine of a network-based computer system, the item datarelated to an item categorized in at least a first category of aplurality of categories supported by the network-based computer systemand including an item price-based value associated with the item; meansfor determining a category-specific threshold price-based value of thefirst category; means for automatically determining at the machine thatthe item data is irregular, based on the item price-based value and thecategory-specific threshold price-based value; and means, responsive tothe determination that the item data is irregular, for setting anirregular item flag of the item data.
 37. A system comprising: adatabase to receive and store item data, the item data related to anitem categorized in at least a first category of a plurality ofcategories supported by a network-based computer system and including anitem price-based value associated with the item; a database engineserver including an irregular activity monitoring system, the irregularactivity monitoring system to: determine a category-specific thresholdprice-based value of the first category; determine that the item data isirregular, based on the item price-based value associated with the itemand the category-specific threshold price-based value of the firstcategory; and responsive to the determination that the item data isirregular, set an irregular item flag of the item data.
 38. The systemof claim 37, wherein the irregular activity monitoring system restrictsan entity associated with the item from using the network-based computersystem.
 39. The system of claim 37, wherein the irregular activitymonitoring system stores an entity identification of the entityassociated with the item in an irregular entity database.
 40. The systemof claim 37, wherein the irregular activity monitoring systemcommunicates an electronic message to an entity associated with theitem.
 41. The system of claim 40, wherein the irregular activitymonitoring system sends an e-mail message to at least one of a seller ora buyer of the item, the e-mail message addressed to an addressassociated with the at least one of the seller or the buyer of the item.42. The system of claim 37, wherein the irregular activity monitoringsystem determines that the item data is legitimate; and responsive tothe determination that the item data is legitimate, unsets the irregularitem flag of the item data.
 43. The system of claim 37, wherein the itemprice-based value is a price of the item, the price of the item being atleast one of a selling price or a bid price.
 44. The system of claim 37,wherein the item price-based value is a fee set by the network-basedcomputer system based on a selling price of the item.
 45. The system ofclaim 37, wherein the irregular activity monitoring system removes theitem data determined to be irregular from an item database of thenetwork-based computer system.
 46. The system of claim 37, wherein theirregular activity monitoring system generates a report based on atleast one of the item data or an item database of the network-basedcomputer system, the item data determined as irregular.
 47. The systemof claim 37, wherein the irregular activity monitoring system, indetermining the category-specific threshold price-based value, reads thecategory-specific threshold price-based value from a table ofprice-based values.
 48. A machine-readable medium comprising a set ofinstructions, which when executed by one or more processors of a machineat a network-based computer system, causes the machine to: receive itemdata at the network-based computer system, the item data related to anitem categorized in at least a first category of a plurality ofcategories supported by the network-based computer system and includingan item price-based value associated with the item; determine acategory-specific threshold price-based value of the first category;automatically determine at the machine that the item data is irregular,based on the item price-based value and the category-specific thresholdprice-based value; and responsive to the determination that the itemdata is irregular, set an irregular item flag of the item data.